Rep. Herbert E. Harris II, Sen. Harry Byrd Jr. and the Prince William County Supervisors have become so thoroughly entangled in the fight over the Manassas Battlefield National Park expansion that none of them may escape unharmed.

But while these principal antagonists maneuver in the final stages of a two-year battle, the park seems on the verge of gaining the protection from development that preservationists have demanded.

The latest development is a statement from Byrd that "as a Virginian I am proud of Manassas Battlefield Park and favor the concept of a reasonable expansion consistent with the views and the needs of the people of Prince William County."

Byrd refused to elaborate on that statement, but it appeared to be a call for a compromise from the Virginia Independent, who until now has refused to say whether he favors expansion, to the Prince William Supervisors.

Byrd, joined by Sen. William L. Scott (R-Va.), has been able to bottle up in committee at the supervisors' request the House-passed bill, which would add about 1,700 acres to the 3,000-acre park.

The proposal authorizes $8.5 million to fill out the park's southern boundary to I-66, protect the eastern, Bull Run boundary in Fairfax County and add a farm where the Second Battle of Bull Run began.

Exercising "senatorial courtesy," which allows U.S. senators to block a bill affecting only their state, Byrd and Scott have kept the bill from coming up for a Senate vote despite strong support for the measure by Sen. James Abourezk, chairman of the subcommittee responsible for national parks legislation.

But last week Harris and Rep. Phillip Burton, chairman of the House parks subcommittee, add the Manassas bill to a billion-dollar omnibus parks bill.

That maneuver made certain that a version of the Harris bill will go to a Senate-House conference where the final form of the bill be worked out.

Senate sources say that if Byrd and Scott continue to oppose the Mansassas legislation it will not be included in the Senate bill. But they say that the Senate conferees would be willing to accept the House Language, thereby breaking the Byrd-Scott hold.

That turn of events was followed by Bryd's statement in favor of the "concept" of expansion. Byrd, under editorial attack for blocking the bill and under pressure from the United Daughters of the Confederacy, evironmental and historical groups, also sought to shore up his pro-parks reputation.

"Through the years, I have been a strong advocate of our national parks, both recreational and historical," Byrd said. "I sponsored the legislation which created the Shenandoah Wilderness and have worked with the National Park Service and local authorities on other conservation efforts."

Byrd, getting squeezed on an issue that holds small potential for political profit, appears to be looking for a way to solve the dispute that would satisfy both the supervisors and the bill's supporters.

The supervisors, however, may make things tough for Byrd. Three of the seven members said recently that they will oppose by compromise. And a fourth, Chairman Donald White, said he was totally against the expansion but might consider a compromise "if we are going to get it jammed down our throats anyway."

The supervisors also find themselves in a squeeze because the version of the expansion that has passed the House takes into the park Sudley United Methodist Church, a privately owned cemetery and a farm which the county wants part of for a highway bypass. The church and the cemetery don't want to be in the park.

If the County Board does not agree to a compromise, the only version of the bill in conference will be the broad one. And should that become law, the church members might look back and decide that the board should have compromised. If the board members do compromise, however, they may be vulnerable to attack on grounds of abandoning their principles.

One way out might be to avoid a public vote, go quietly to Byrd and ask him to have the measure amended on the Senate side, assuring its eventual passage.

Whatever they do, most of the supervisors have become, if they were not already, bitter opponents of Harris, who is up for reelection this fall. Most of the opponents of the park expansion have throughout the debate linked their attacks to political assaults on Harris.

No politician like anemies, but Harris may profit from the election support of the environmentalists and conservation groups who favor his bill.

Harris says, "I think the purpose of the bill is important. Preservation of land has always been politically difficult. I've always had the attitude you have to do what is right and let the chips fall where they may."

Harris, when his plan was added to the omnibus parks bill, asked the Senate to make a series of changes that he says answers the complaints of the expansion opponents.

Board Chairman White counters that the changes Harris proposes were first developed by the board and adds that the changes may not be sufficient.

And a spokesman for Byrd, when asked what the senator will do if the supervisors reject a compromise, replied, "I just have no comment on that."